The primary long-term goal of this project is to improve a wide range of dental clinical procedures through the use of glass fiber-reinforced thermoplastic composites (FRC). The FRC will be used as wires, bars, clasps, and frameworks in applications such as retainers, splints, space maintainers, orthodontic archwires and prosthodontic devices. FRC possess a unique combination of properties for dental applications, including good mechanical properties, esthetics and the potential for chair-side formability and bonding to tooth structure. In fulfilling this goal the structure-property relationships of these systems will be examined carefully. FRC formulations with the desired characteristics for each application will be developed by studying the effects of thermoplastic matrices (PETG,PC, PU, PCTG, Nylon 6), fiber loadings (30-70%) and coupling agents. Samples will be prepared in the laboratory with an automated solvent-cast/filament- winding technique. Evaluations will be conducted microscopically (optical, SEM, image analysis); mechanically (flexure, tensile, torsion, stress relaxation); and physically (water sorption, hydrolytic stability, formability). Samples of some formulations will be produced by pultrusion and compared to the analogous laboratory specimens to determine if the filament-winding technique is a useful, predictive model system. The effects of specimen geometry on measured properties will also be studied. The effects of various organosilane surface treatments on fiber/matrix interfacial behavior will be characterized for different thermoplastic resins and types of fibers, under dry and wet conditions. The technique of mechanically testing a single fiber embedded in a matrix will be used. Surfaces will be evaluated with transmission and diffuse reflectance FTIR.